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101.
H. Caps H. Decauwer M.-L. Chevalier G. Soyez M. Ausloos N. Vandewalle 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):115-119
We report an experimental study of aqueous foam imbibition in microgravity with strict mass conservation. The foam is in a
Hele-Shaw cell. The bubble edge width ℓ is measured by image analysis. The penetration of the liquid in the foam, the foam
imbibition, the foam inflation, and the rigidity loss are shown all to obey strict diffusion processes. The motion of bubbles
needed for the foam inflation is a slow two-dimensional process with respect to the one-dimensional capillary rise of liquid.
The foam is found to imbibes faster than it inflates.
Received 20 May 2002 / Received in final form 21 January 2003 Published online 23 May 2003
RID="a"
ID="a"e-mail: herve.caps@ulg.ac.be 相似文献
102.
The axisymmetric and plane extrusion flows of a liquid foam are simulated assuming that the foam is a homogeneous compressible
Newtonian fluid that slips along the walls. Compressibility effects are investigated using both a linear and an exponential
equation of state. The numerical results confirm previous reports that the swelling of the extrudate decreases initially as
the compressibility of the fluid is increased and then increases considerably. The latter increase is sharper in the case
of the exponential equation of state. In the case of non-zero inertia, high compressibility was found to lead to a contraction
of the extrudate after the initial expansion, similar to that observed experimentally with liquid foams and to decaying oscillations
of the extrudate surface. The time-dependent calculations show that the oscillatory steady-state solutions are stable. These
steady-state oscillatory solutions are not affected by the length of the extrudate region nor by the boundary condition along
the wall. 相似文献
103.
We identify the minimum-perimeter periodic tilings of the plane by equal numbers of regions (cells) of areas 1 and λ (minimal
tilings), with at most two cells of each area per period and for which all cells of the same area are topologically equivalent.
For λ close to 1 the minimal tiling is hexagonal. For smaller values of λ the minimal tilings contain pairs of 5/7, 4/8 and
3/9 cells, the cells with fewer sides having smaller area. The correlation between area fraction and number of sides in the
minimal tilings is approximately linear and consistent with Lewis' law.
Received 27 June 2001 and Received in final form 29 August 2001 相似文献
104.
C. Nardin J. Widmer M. Winterhalter W. Meier 《The European physical journal. E, Soft matter》2001,4(4):403-410
Self-assembly of an amphiphilic triblock copolymer carrying polymerizable end-groups is used to prepare nanometer-sized vesicular
structures in aqueous solution. The triblock copolymer shells of the vesicles can be regarded as a mimetic of biological membranes
although they are 2 to 3 times thicker than a conventional lipid bilayer. Nevertheless, they can serve as a matrix for membrane-spanning
proteins. Surprisingly, the proteins remain functional despite the extreme thickness of the membranes and that even after
polymerization of the reactive triblock copolymers. This opens a new field to create mechanically stable protein/polymer hybrid
membranes. As a representative example we functionalize (polymerized) triblock copolymer vesicles by reconstituting a channel-forming
protein from the outer cell wall of Gram-negative bacteria. The protein used (OmpF) acts as a size-selective filter, which
allows only for passage of molecules with a molecular weight below 400 g mol-1. Therefore substrates may still have access to enzymes encapsulated in such protein/polymer hybrid nanocontainers. We demonstrate
this using the enzyme β-lactamase which is able to hydrolyze the antibiotic ampicillin. In addition, a transmembrane voltage
above a given threshold causes a reversible gating transition of OmpF. This can be used to reversibly activate or deactivate
the resulting nanoreactors.
Received 22 August 2000 相似文献
105.
Arthur N. Wilkinson Nurul H. Fithriyah John L. Stanford Daniel Suckley 《Macromolecular Symposia》2007,256(1):65-72
Summary: Polyurethane foam nanocomposites were formed via in-situ copolymerisations, in which polyether polyol/water-montmorillonite mixtures were reacted with toluene diisocyanate. The unmodified Na+- montmorillonite (MMT) was swollen in polyol/water using an ultrasound technique resulting in intercalated layers with increased basal spacings of 2.3 ± 0.1 nm. Measurements of quasi-adiabatic temperature rise showed higher reaction rates as MMT loading increased from 0 to 10 wt.-%. Forced-adiabatic FTIR spectroscopy was used to determine the kinetics of both the copolymerisation and of the microphase separation between poly(ether-urethane) soft segments and polyurea hard segments. The apparent microphase-separation transition time decreased from 70 ± 3 to 42 ± 2 s upon addition of ≤10 wt.-% MMT, but at reaction times >100 s there was significant retardation of the development of hydrogen bonding in the urea groups of the hard-segment phase. 相似文献
106.
107.
Ye Hua Shengmiao Zhang Yun Zhu Yeqian Chu Jianding Chen 《Journal of polymer science. Part A, Polymer chemistry》2013,51(10):2181-2187
Open‐cell hydrophilic polymer foams are prepared through oil‐in‐water Pickering high internal phase emulsions (HIPEs). The Pickering HIPEs are stabilized by commercial titania (TiO2) nanoparticles with adding small amounts of non‐ionic surfactant Tween85. The morphologies, such as average void diameter and interconnectivity, of the foams can be tailored easily by varying the TiO2 nanoparticles and Tween85 concentrations. Further, investigation of the HIPE stability, emulsion structure and the location of TiO2 nanoparticles in resulting foams shows that the surfactant tends to occupy the oil‐water interface at the contact point of adjacent droplets, where the interconnecting pores are hence likely to be formed after the consolidation of the continuous phase. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
108.
Preparation of emulsion‐templated fluorinated polymers and their application in oil/water separation
《Journal of polymer science. Part A, Polymer chemistry》2018,56(14):1508-1515
A series of emulsion‐templated fluorinated polymers (polyHIPEs) were first synthesized with introducing 2‐(perfluorohexyl)ethyl methacrylate (PEM) to the external phase of water‐in‐styrene high internal phase emulsion (HIPE) templates. The morphology (i.e., void size and its distribution) of these porous materials could be tuned simply by changing PEM and/or surfactant amount. The synergistic effect between the surface chemistry and surface architecture allowed the polyHIPEs to possess hydrophobicity with a water contact angle of 151°. The superhydrophobicity and oleophilicity of the polyHIPEs, together with their highly open porous structure, make the material a very competitive candidate as a filtration material for oil/water separation in practice with the efficiency of separating dichloromethane from the oil/water mixture of 95%. Such oil/water separating capacity was maintained after 10 cycles of filtration of oil/water, indicating the cyclic usage of the polyHIPE is feasible. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1508–1515 相似文献
109.
《Angewandte Chemie (International ed. in English)》2017,56(49):15520-15538
Low‐density macroporous sponges with densities less than 100 mg cm−3 are both a challenge and an opportunity for advanced chemistry and material science. The challenge lies in the precise preparation of the sponges with property combinations that lead to novel applications. Bottom‐up and top‐down chemical and engineering methods for the preparation of sponges are a major focus of this Review, with an emphasis on carbon and polymer materials. The light weight, sustainability, breathability, special wetting characteristics, large mass transfer, mechanical stability, and large pore volume are typical characteristics of sponges made of advanced materials and could lead to novel applications. Some selected sponge properties and potential applications are discussed. 相似文献
110.